Is Internal Energy Change Consistent for Different Paths in Thermodynamics?

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    Thermodynamics
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Homework Help Overview

The discussion revolves around the concept of internal energy change in thermodynamics, specifically examining whether the change in internal energy is consistent for different paths taken between two states in a system. The problem involves calculating pressure differences based on given heat and work values along specified paths.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between heat, work, and internal energy, questioning how to calculate the change in internal energy for different paths. Some participants express confusion over their calculations and seek clarification on the implications of internal energy being a state function.

Discussion Status

The discussion is ongoing, with participants attempting various calculations and expressing uncertainty about their results. Some guidance has been offered regarding the visibility of the diagram, and questions about the nature of internal energy as a state function have been raised, indicating a productive exploration of the topic.

Contextual Notes

Participants note the lack of visibility of the diagram referenced in the problem, which may be affecting their ability to interpret the scenario accurately. There is also mention of specific values for heat and work along different paths, which are central to the calculations being discussed.

2Pac
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When a system is taken from state i to state f along the path iaf as shown in the figure, it is found that Qiaf = 53.6 cal and Wiaf = 30.5 cal. Along the path ibf, Qibf = 38.0 cal.
If the difference in volume between states i and b is 0.023 m3, what is the pressure dufference between states b and f?
 

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I found the work done along the path ibf to be 14.9cal, converted that to J and divided by .023m^3 to get a pressure in PA. converted 30.5 cal to joules and divided by .023m^3 again. subtracted the two... answer is incorrect. so if that isn't the answer how do i go about solving this?
 
you might want to settle down for a minute, none of us can see your diagram at this time.
 
diagram looks like this:
PHP:
    ^
|    a__________________________ f
|     |                          |
|     |                          |
P     |                          |
|     |                          |
|     |__________________________| 
|    i                            b
|_____________________________________>
0                        V
 
I guess i'll give you another day to help me out. :-p
 
change internal energy is a state function right, would the change in internal energy be equal for iaf and ibf? If so, how can you calculate the change in internal energy, and from this how can you calculate the pressure difference?
 

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